[U-Boot] [PATCH 1/4] dm: gpio: extend gpio api by dm_gpio_set_pull()

[Stephen Warren]

On 02/17/2015 10:01 PM, Simon Glass wrote:
> +Stephen who might have an opinion on this.
>
> Hi Przemyslaw,
>
> On 17 February 2015 at 06:09, Przemyslaw Marczak <p.marczak at samsung.com> wrote:
>> This commits extends:
>> - dm gpio ops by: 'set_pull' call
>> - dm gpio uclass by: dm_gpio_set_pull() function
>>
>> The pull mode is not defined so should be driver specific.
>
> It's good to implement this, but I think you should try to have a
> standard interface. You could define the options you want to support
> and pass in a standard value.
>
> Otherwise we are not really providing a driver abstraction, only an interface.

I don't think that pull is a GPIO-related function/property. At least on 
Tegra, the GPIO controller allows you to set the pin direction and the 
output value and that's it. Configuring pull-up/down and other IO 
related properties is done in the pinmux controller instead. I don't 
think we want a standard API that has to touch both HW modules at once. 
What common code needs to manipulate a GPIO's pull-up/down setting? As 
precedent observe that pull-up/down isn't part of the Linux kernel's 
GPIO API, but rather that's part of the SoC-specific pinctrl driver, 
which controls pinmuxing etc.